Self-cleaning oven with smoke eliminator



United States Patent Filed Francis L. Faehling;

Stanley 0. Peterson, Wisconsin Rapids, Wis.

Dec. 18, 1968 Dec. 22, 1970 Preway Inc.

a corporation of Wisconsin Inventors Appl. No.

Patented Assignee SELF-CLEANING OVEN WITH SMOKE ELIMINATOR 1 Claim, 2Drawing Figs.

US. Cl. 219/393, 23/288: 2l9/4i2 hit. F27d 11/02 Field ofSearch 219/397,

References Cited UNITED STATES PATENTS ll/l 942 Ames 219/392 ll/l952Ames.... 219/395 1/1960 Walkoe..... 219/393 8/ l 967 Hurko 219/3972/1969 Hurko et a1 2 l 9/397X FOREIGN PATENTS 2/1940 Switzerland 2 l 9/396 Primary Examiner-Velodymyr Y. Mayewsky Altomey-l-lofgren, Wegner,Allen, Stellman and McCord ABSTRACT: A self-cleaning oven having a smokeeliminator with a catalytic element effective on heating and a broilelement positioned adjacent the top of the oven and adjacent said smokeeliminator and operable a large part of the time during a self-cleaningcycle to generate sufficient heat to activate the catalytic elementdirectly from the broil element, without any separate heating circuitfor the catalytic element.

SELF-CLEANING OVEN WITH SMOKE ELIMINATOR BACKGROUND OF THE INVENTIONThis invention pertains to self-cleaning ovens and, more particularly,to a smoke eliminator for use with such ovens wherein the heatresponsive catalytic element of the smoke eliminator is activated byheat derived from the broil element of the oven.

A majority of the self-cleaning ovens on the market have heat elementsoperable at a rated voltage of approximately 240 volts, but during aself-cleaning cycle are operated continuously at 120 volts to avoidthermal shock. These ovens, as well as those that operate the broilelement at rated voltage periodically during the self-cleaning cycle,have not had provision for activation of the smoke eliminator from heatgenerated directly by the broil element but have relied upon a separateheater for energizing the catalytic element of the smoke eliminator.This, of course, .requires additional components and circuitry to causeeffective operation of the smoke eliminator.

SUMMARY OF THE INVENTION An object of this invention is to provide a newand improved smoke eliminator wherein a catalytic element thereof can bedirectly activated by heat derived from a broil element constructed andlocated adjacent the smoke eliminator to provide sufficient heatingthereof.

An additional object of the invention is to provide a selfcleaning ovenhaving an outlet passage from the top of the oven chamber, with a smokeeliminator positioned at the entrance to the outlet passage and having acatalytic element effective upon sufiicient heating and a broil unitpositioned adjacent the top of the oven chamber and having a pluralityof lengths thereof and an interconnecting curved section positioneddirectly beneath the smoke eliminator whereby intermittent cycling ofthe broil element at full rated voltage provides sufficient wattage toheat and activate the catalytic element.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective view of an ovenof the built-in type mounted in a cabinet with a part of the oven doorbroken away; and

FIG. 2 is a vertical section, taken generally along the line 2-2, inFIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT A front trim frame of theself-cleaning oven has a control panel 11 at the upper front thereofmounting suitable control knobs 15 for controlling the variousoperations of the oven, with a control box 16 located to the rear of thecontrol panel and housing the necessary circuitry. This control boxincludes circuitry to operate the oven in a self-cleaning cycle. Thecircuit is well known in the an and includes a timer (not shown) forcontrolling the length of the self-cleaning cycle and circuitry tooperate the broil element at a percentage input of rated voltage.

The oven includes interior walls, including a top wall 20, a bottom wall21 and a rear wall 22. One of the sidewalls 23 is shown in the drawings.These walls are surrounded by an insulating casing (not shown) toinsulate the oven chamber defined by the aforementioned walls from thesurrounding cabinet, or other adjacent structure. The top wall 20 of theoven has an opening near the rear thereof to which an upwardly recessedcap 25 is fitted and which defines the entrance of an outlet passagefrom the oven. An upwardly-opening outlet 26 from the cap connects toother structure (not shown) for conveying gases from the oven.

A smoke eliminator 27 is positioned beneath the opening in the top wall20 and secured thereto whereby gases leaving the oven must pass throughthe smoke eliminator in the exhaust path from the oven. This smokeeliminator is necessary in a selfcleanmg oven because of the smokegenerated during the high temperature bum-off of material within theoven, and is a commercially available device. A typical device is thatoffered by the Ucinite Co. and which has a spirally-wound ribbon ofstainless steel with a catalytic element disposed within a cylindricalopen-ended housing which becomes effective to eliminate smoke uponreaching a predetermined temperature.

The heating of the catalytic element is accomplished without the use ofany separate circuitry and solely by the use of a broil element,indicated generally at 30, located adjacent the top wall 20 of the ovenand having, in the illustrated embodiment, a series of element lengths3l-36 for a total of six element lengths which are connected by curvedsections 37- --41 disposed alternately at opposite ends of the broilelement. As seen in FIGS. I and 2, the interconnecting curved section 38is disposed directly beneath the smoke eliminator and its catalyticelement. This positions a sufficient amount of broil element surfaceadjacent the smoke eliminator whereby the broil element will heat thecatalytic element to render it effective to eliminate smoke. Other broilelements with a different number of lengths could be used.

It has been found that operating the broil element 30 at voltscontinuously does not provide a high enough surface temperature on thebroil element to activate the catalytic element since the conventionaloutput of such a element is approximately 750 watts. With elementoperated at 240 volts, the element need only operate periodically duringthe cleaning cycle and more specifically approximately 40 percent of thetime or more provides a sufficiently high surface temperature on thebroil element to activate the catalytic element of the smoke eliminator.As examples, a 3500 watt broil element has performed satisfactorilyoperating at 45 50 percent input at rated voltage. Also, a 3000 wattbroil element operated at 60 percent input at rated voltage providesapproximately 1800 watts and has performed satisfactorily.

We claim:

1. In a self-cleaning oven, a smoke eliminator located beneath an outletpassage for the oven and having a catalytic oxidation element effectiveupon reaching a predetermined temperature, an electric broil elementhaving a rated voltage of approximately 240 volts mounted in the upperpart of said oven and having a pair of adjacent lengths and a curvedinterconnecting section directly disposed and closely spaced beneath thesmoke eliminator in unobstructed heat exchange relation therewith, andelectrical means for operating the broil element intermittently in aself-cleaning cycle at approximate ly 40 percent or more input at ratedvoltage to provide the heat needed to activate the catalytic element.

